Fructo-oligosaccharides are a class of non-digestible carbohydrates or sugars that occur naturally in a wide variety of foods. Fructo-oligosaccharides are composed of glucose units, to which are bound one, two, three or four fructose units. Fructo-oligosaccharides may be trisaccharides (GF2, 1-kestose), tetrasaccharides (GF3, nystose) and pentasaccharides (GF4 (fructofuranosil nystose). These sugars can be found in large quantities in foods such as asparagus, banana, garlic, onion, tomato and wheat.
Fructo-oligosaccharides are commercially available as a nutritional supplement and has a Generally Recognized as Safe (GRAS) status. Fructo-oligosaccharides have about half the natural sweetness of sugar but provide almost no calories since they cannot be digested by humans. Because of these properties fructo-oligosaccharides are used as an artificial sweetening agent in cookies, cakes, breads, candies, dairy products and some drinks. Fructo-oligosaccharides are also used as flavor enhancer, bulking agent and humectants.
Since they are non-digestible, fructo-oligosaccharides pass through the human digestive system virtually unchanged. When these sugars reach the colon, they are utilized by the beneficial bacteria (known as Bifidobacteria or Bifidus) found in the colon for growth and multiplication. This enhances digestion, helps in detoxification and elimination processes, and helps to boost the immune system. Moreover, fructo-oligosaccharides decrease the pH of the intestinal content which helps in calcium and magnesium absorption.
Fructo-oligosaccharides may be produced from sucrose via a transformation reaction catalyzed by a beta-fructofuranosidase/fructosyltransferase enzyme. This enzyme catalyses the transfer of a fructosyl group from a donor to a receptor, which may be sucrose or a fructo-oligosaccharides, such as kestose, nystose to form fructo-oligosaccharides.
The beta-fructofuranosidase/fructosyltransferase enzyme used in the production of fructo-oligosaccharides may be obtained from the cultures of fungi different species, such as (Aspergillus, Pennicillium, Fusarium, Gloesporium), from the cultures of yeasts, such as (Saccharomyces, Rhodotorulla, Pichia, Hansenula, Candida and Aureobasidium), and from some plants, such as asparagus. Whole microbial cells or isolated enzyme may be used for the production of fructo-oligosaccharides.
However, fructo-oligosaccharides that are produced by such methods contain certain amounts of free glucose and fructose in addition to the fructo-oligosaccharides. Therefore, to get high content fructo-oligosaccharides, additional separation processes are needed which adds to the cost of the product. Moreover, the glucose and fructose obtained tend to adversely affect the purity of the fructo-oligosaccharides and also inhibit the bioconversion to fructo-oligosaccharides.
Therefore, there is a need for a process for the production of fructo-oligosaccharides that allows for high yield of high purity fructo-oligosaccharides.